1. Field of the Invention
The present invention relates to a videocommunication network between videophone terminals and a picture bank. Each videophonic terminal comprises audiofrequency means connected to a bidirectional telephone channel for transmitting and receiving audiofrequency signals, videofrequency means connected to a wide-band bidirectional channel for transmitting and receiving videofrequency signals, and means connected to the telephone channel for transmitting and receiving data signals. The picture bank comprises means selectively connected to one of several bidirectional telephone channels for transmitting and receiving data signals and means selectively connected to one of several wide-band channels for transmitting videofrequency signals.
2. Description of the Prior Art
In known videocommunication networks of this type, once the videocommunication link has been established between a subscriber videophone terminal and the picture bank through the exchange of data signals in compliance with a videotex protocol in telephone lines or channels, a wide-band communication link connects, the via wide-band switching units in the network, the picture bank videofrequency signal transmitting means to the terminal videofrequency signal receiving means. Throughout the videocommunication, which lasts generally a long time, the terminal telephone line is connected to the corresponding picture bank telephone line, with a view to possibly exchange data, especially for selecting recorded programs in the picture bank.
Under these conditions, the subscriber cannot use the local telephone line as normal for an audio dialog with another subscriber.
Additionally, the vision representing signals transmitted by the picture bank are routed by the videophone switching means within the network, which can give rise to congestion of the initially planned traffic for the purely videophone communications, the duration of the videocommunication with the picture bank being very long.